Damped Corrections to Inflationary Spectra from a Fluctuating Cutoff

TL;DR

This paper studies how a finite width in the UV cutoff, due to quantum gravity effects, damps trans-Planckian corrections to inflationary spectra, affecting observable oscillations in the CMB.

Contribution

It introduces a damping mechanism for superimposed oscillations in inflationary spectra caused by a finite-width UV cutoff, a novel consideration in trans-Planckian physics.

Findings

Damping reduces the amplitude of oscillations in the CMB spectra.

The damping effect depends on the UV cutoff's variance.

Observation of oscillations constrains the UV cutoff's width.

Abstract

We reconsider trans-Planckian corrections to inflationary spectra by taking into account a physical effect which has been overlooked and which could have important consequences. We assume that the short length scale characterizing the new physics is endowed with a finite width, the origin of which could be found in quantum gravity. As a result, the leading corrections responsible for superimposed osillations in the CMB temperature anisotropies are generically damped by the blurring of the UV scale. To determine the observational ramifications of this damping, we compare it to that which effectively occurs when computing the angular power spectrum of temperature anisotropies. The former gives an overall change of the oscillation amplitudes whereas the latter depends on the angular scale. Therefore, in principle they could be distinguished. In any case, the observation of superimposed oscillations would place tight constraint on the variance of the UV cutoff.